Question: Solve for $x$ and $y$ using substitution. ${x-3y = -5}$ ${x = -3y-11}$
Since $x$ has already been solved for, substitute $-3y-11$ for $x$ in the first equation. ${(-3y-11)}{- 3y = -5}$ Simplify and solve for $y$ $-3y-11 - 3y = -5$ $-6y-11 = -5$ $-6y-11{+11} = -5{+11}$ $-6y = 6$ $\dfrac{-6y}{{-6}} = \dfrac{6}{{-6}}$ ${y = -1}$ Now that you know ${y = -1}$ , plug it back into $\thinspace {x = -3y-11}\thinspace$ to find $x$ ${x = -3}{(-1)}{ - 11}$ $x = 3 - 11$ ${x = -8}$ You can also plug ${y = -1}$ into $\thinspace {x-3y = -5}\thinspace$ and get the same answer for $x$ : ${x - 3}{(-1)}{= -5}$ ${x = -8}$